If you want to set up wifi with minimum of fuss, just install wicd package (and its dependencies) from the package repository. You will then be able to setup your connection in a user-friendly GUI.
See http://wicd.sourceforge.net/ for detailed information about wicd.

After installing “wicd.tcz” execute the following command to start the wicd daemon:

sudo wicd-start

Then activate the GUI interface using the application menu.

If you have problems getting wicd to see your wifi card, you may have driver issues. Atheros users can see this Network Setup - Atheros Wireless Cards, but note that tinycore 2.0 and later ships with ath5k and ath9k open source drivers that should handle most Atheros cards.

TIP: For a system that doesn't have wired access, you may find it easier to download the wicd package files and its dependencies first and store them some place convenient. You can then load them into tinycore using the tce-load command

Note: As of Tiny Core Linux 4.x you can probably just use the wpa_gui extension from the appbrowser and start the application from wbar. It will automatically start wpa_supplicant and udhcpc for all found wireless devices.

You should configure your network and choose File → Save Configuration. If you want to automatically restart the WPA wireless connection after reboot, put ”/usr/local/etc/init.d/wpa_gui start” to your /opt/bootlocal.sh and put /etc/wpa_gui.conf to your backup. This way it will start wpa_supplicant and udhcpc for your wireless devices with the configured networks. The wpa_gui service can also be en-/disabled from Panel/Services.

Another way to set up a wireless connection is to use wpa_supplicant with it's associated GUI interface. wpa_supplicant is the IEEE 802.1X/WPA component that is used in the client stations. It implements key negotiation with a WPA Authenticator and it controls the roaming and IEEE 802.11 authentication/association of the wlan driver.

wpa_supplicant is designed to be a “daemon” program that runs in the background and acts as the backend component controlling the wireless connection. wpa_supplicant supports a text-based frontend (wpa_cli) and a GUI (wpa_gui).
See http://hostap.epitest.fi/wpa_supplicant/ for more information.

Install wpa_supplicant and wpa_gui. Then configure wpa_supplicant for remote control by creating a configuration file (this has to be done only once):

Create a configuration file ”/opt/wpa.cfg” with the following content:

Prerequisites:
1. You have a working tinycore system with some support for persistence (a tce directory and either a backup/restore point or a persistent /opt directory) ←- link to appropriate howtos
2. Your wireless hardware is supported by a driver available in the repo
3. You want to connect to an open access point, WEP or WPA-PSK secured AP (you do care about security don't you?)

1. boot tinycore and install the needed wireless packages if you haven't already (if you have an Intel wireless card, you need to install firmware-intel.tcz first, and iwlwifi.tcz if it doesn't install it as a dependency).

If you will be installing to a system that depends on wifi access you may find it easier to pre-download these files and copy them to your tinycore tce directory so that they are installed at boot time (or use tce-load to install them after boot).

2. Check whether you can see your wireless hardware. in the console run:

iwconfig

you should see a list of interfaces with some status info. your wireless interface may show up as wlan0 (but maybe ath0 or eth0?). You need to remember the name of this interface as it will be used later

If you don't see a connection, you may need to load or install drivers. The wireless-`uname -r`-tinycore contains all in-kernel wifi drivers. You can verify the drivers are present using something like (assuming Atheros card):

1. To connect to a particular access point, all you need to do is type in the console

iwconfig *interface* essid *network-id*

to search for access points, use the command

iwlist scanning

to connect to the nearest access point, just use:

iwconfig *interface* essid any

2. To finalize the connection (getting IP address etc), go to control panel, open the netcardconfig tool. switch eth0 to the name of your interface (e.g. wlan0). Change “use DHCP Broadcast?” to yes, leave “Save Configuration” as yes. Hit apply. This will save and run a script /opt/*interface*.sh. In addition, the /opt/bootlocal.sh (the script run at boot) will now include /opt/*interface*.sh. If your /opt directory is not persistent, make sure you do a backup when you boot or you will need to rerun this tool each time you boot.

Alternately, instead of running netcardconfig you could just issue the udhcpc command, e.g.,

udhcpc -i *interface*

3. At this point you should have a working network connection. If it doesn't work you might need to play around with the udhcpc commandline (the gui in step 2 makes a udhcpc call, but there are additional options that may be needed)

4. If you don't want to have to run step 1 and 2 every time you boot, you can add the command to your /opt/bootlocal.sh file before the line that calls /opt/*interface*.sh script (make sure you backup!)

Note that this assumes a fairly conventional WPA-PSK setup. If you need to use other security (e.g. WEP) or are connecting to a more sophisticated network you may have to tweak this file. See the wpa_supplicant manual for more info. (What if you connect to more than one WPA-PSK network – can add as many network sections to the conf file as needed)

save it as /opt/wpa_configure.conf (then to ensure it is persistent in the system, add the line opt/wpa_configure.conf to /opt/.filetool.lst)

3. to connect to the access point, run in the console:

wpa_supplicant -i*interface* -c/opt/wpa_configure.conf &

For diagnostic run this command with debugging option -d

sudo wpa_supplicant -i*interface* -c/opt/wpa_configure.conf -d

Close debugging mode with Ctrl+c.
You can verify the connection with iwconfig. After successful association you get all connection data in command output: AP BSSID, Bit Rate, Link Quality etc.
Another simple method is watching card LINK diode. Diode shines with constant light, when Adapter is connected to AP.

4. now to finalize the connection (getting IP address etc), go to control panel, open the netcardconfig tool. switch eth0 to the name of your interface (e.g. wlan0). Change “use DHCP Broadcast?” to yes, leave “Save Configuration” as yes. Hit apply. This will save and run a script /opt/*interface*.sh. In addition, the /opt/bootlocal.sh (the script run at boot) will now include /opt/*interface*.sh. If your /opt directory is not persistent, make sure you do a backup when you boot or you will need to rerun this tool each time you boot.

Alternately, instead of running netcardconfig you could just issue the udhcpc command, e.g.:

udhcpc -i *interface*

5. At this point you should have a working network connection. If it doesn't work you might need to tweak the wpa_supplicant configuration or the udhcpc command line.

6. If you don't want to have to run step 3 and 4 every time you boot, you can add the wpa_supplicant command in line 3 to your /opt/bootlocal.sh file before the line that calls /opt/*interface*.sh script (make sure you backup!)